Devices, such as mobile phones and tablets, often have limited internal memory for storing files. In order to compensate for the limited internal memory, such devices often provide for expanding the storage capacity of the device using external memory cards, such as Secure Digital (SD) memory cards. While external memory cards can significantly increase the storage capacity of the device, they can also be the source of security problems.
External memory cards can be formatted with a file system that does not support access restrictions. An example of such a file system is the File Allocation Table (FAT) file system. When using a file system that does not support access restrictions, it may be possible for an application running on a device, such as a mobile phone, to access files on the external memory card that are not intended to be accessed by the application, such as files written by a different application or files written by an operating system.
Therefore, there exists ample opportunity for improvement in technologies related to accessing external storage on computing devices.